Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

DIY: Do It Yourself Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

Well, every time I had a passenger in my car I got the really annoying airbag light on my dash. This is due to the sensors in the passenger seat failing or having failed. The seat has a mat inside it that can detect the presence of a person. Now this has broken the ECU detects that and puts the airbag light on. The bypass units can be bought on ebay very cheaply, mine was £5 delivered. They are basically just a small resistor to imitate the resistance created when a passenger sits in the seat. They are used to control the deployment of the passenger airbags. A crash with no passenger means no passenger airbags deployed saving on repair costs. Now this unit is fitted the airbags will always deploy as it always thinks there is a passenger (better than the other way round). The only downside is now you can't put a baby seat up front due to the airbag deployment. This, however, wasn't an issue for me and is way better than the £480 BMW wanted to fix it.

Any way, on with the DIY!

You will need:

Airbag occupancy sensor bypass unit
Maybe some tape/zip ties
Snips

Okay first up you need to roll the seat forward as far as possible then tilt it forward as much as you can. You don't need to go mad and push it forward there should be enough room if you lay down on the back seats. In this picture my fingers are on the connector unit that you will be working on:

If you look under the seat its right on the back side closest to you, ignore all the cables in the middle underneath. This is the unit you need to find:

At the top of the image above are a blue and white wire. These wires come out of the box (left side as you look at the image) and in to a connector block. The right side of the connector block needs to be unclipped and pull as much slack as you can out. This is the connector hanging down here, excuse the really bad photo:

Here is the connector cut off, leave yourself a couple of inch of wire on it:

Here is the bypass unit I will be connecting:

Mine came with some crimping blocks that needed to simply have each wire inserted and crimped shut. You may need to strip and twist them together then insulate with tape. Either way is fine and should look like this:

Now simply plug the connector back in to the unit and zip tie or tape the wires out of the way. Enjoy no more airbag lights!!

if somebody is little bit more skilled, he can do it himself and not buying things from eBay.

I did some research by measuring the ocupancy sensor which was okay, and figured out which components You need to bypass the sensor if it is broken.

So You need soldering iron, not shaking hands and one 3k3 to 30k resistor and diode 1N4007.

schematic diagram is in the picture

CAUTION:

this is modded bypass modul that was previously posted on some forums, but that "OLD" one caused the airbag light off but the seat was in control unit of airbags NOT OCCUPIED. therefere I did this mod which will make the seat "OCCUPIED" even if nobody is there!!!!!